This invention relates to the use of a refrigerant cycle to cool a lubricant in a driveline component such as an axle or a transmission.
In driveline components, a number of parts rotate relative to other parts at relatively high speeds. A lubricant is typically deposited into a component housing to cool as well lower friction between these rotating parts. During operation of a vehicle incorporating such a component, the temperature of the lubricant will frequently become quite high.
Various methods have been disclosed to cool the lubricant. As an example, it has been proposed to pump the lubricant out of the axle housing for cooling. In these systems, separate lubricant coolers and associated flow lines, have been proposed.
However, these systems add too much cost and extract power from the vehicle.
In a disclosed embodiment of this invention, an effective refrigerant cycle is utilized to cool a lubricant in a driveline component. In particular, an enclosed reservoir including a second fluid distinct from the lubricant is provided in a housing which receives the driveline component. The lubricant is in contact with the reservoir. Heat is transferred from the refrigerant to the lubricant, resulting in heating of the refrigerant and cooling of the lubricant.
The refrigerant vaporizes and is driven from the reservoir through flow lines to a cooling chamber. Preferably, the cooling chamber is placed at a location where it will be exposed to cooling airflow. The cooling chamber acts as a condenser. The refrigerant becomes liquefied and returns to the reservoir. In a disclosed embodiment, the driveline component is an axle housing, including a differential associated housing structure, axle shafts, etc. Most preferably, the reservoir is positioned within an end cap housing of the axle, and outwardly of the differential. Typically, a drive pinion for the differential is located on one lateral side of this bowl cover, and a space is provided on the other lateral side of the end housing. The reservoir is preferably positioned into this space. Thus, no significant additional space is required for the inclusion of the second refrigerant.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.